Retracting screw assembly

Abstract

A retracting screw assembly 10 for maintaining a screw 12 in the retracted position so that flame proof surface 28 is not scratched during opening and closing cover 18. Retracting screw assembly is comprised of a screw 12 with a threaded portion 34, washer 14, conical spring 16. When threaded portion 34 is disengaged from body portion 26, conical spring 16 pulls screw 12 into a retracted position so that threaded portion 34 rests against shoulder 20.

I claim: 
     
       1. A retracting screw assembly for use in explosion-proof enclosures comprising: a screw having a head, a shank, and a threaded portion on that end opposite said head;   a washer having an aperture for receiving said shank and threaded portion and engaging said head;   a conical spring having coils receiving said shank and being coiled from a minor diameter coil to a major diameter coil, said coils becoming nested within said major diameter coil upon full compression;   a cover on said enclosure having an aperture with a restricted opening adjacent the outer face of said cover, said spring being mounted between said cover and said washer;   a body portion on said enclosure having a threaded aperture adapted for alignment with said cover aperture;   a shoulder formed by said restricted opening on said cover;   retaining means on said threaded portion for engaging said shoulder;   said threaded portion threadingly engaging said threaded aperture and causing said head and washer to compress said spring and cause said coils to nest within said major diameter coil, said washer engaging one side of said nested coils and said cover face engaging an opposite side of said nested coils;   whereby upon said threaded portion being disengaged from said threaded aperture of said body, said retaining means is pulled against said shoulder by said spring.   
     
     
       2. A screw assembly as in claim 1 wherein said washer is integral with said screw. 
     
     
       3. A retracting screw assembly as in claim 1 wherein said washer is a separate part of said screw. 
     
     
       4. The retracing screw assembly as in claim 1 wherein said retaining means includes a retaining member disposed on said screw above said threaded portion. 
     
     
       5. The retracting screw assembly as in claim 1 wherein said major diameter coil has an outer diameter greater than the diameter of said washer whereby said conical spring when nested evenly transfers the force between said washer and said cover face. 
     
     
       6. The retracting screw assembly as in claim 1 wherein the diameter of said restricted opening is smaller than the diameter of said minor diameter coil. 
     
     
       7. The retracting screw assembly as in claim 1 wherein said body portion includes a counterbore adjacent said threaded aperture.